Capacitive and inductive load impedances on output drivers of conventional memory cards result in weak output eye performance at high frequencies. Distortion caused by pins, connectors and traces from the memory card across a data bus to other circuitry limits an upper frequency for reliable data transmission. Degradation of the output eye results in poorer receiver margin tests. In conventional driver designs, single symmetrical emphasis techniques are implemented to deal with the degradation. Increasing a drive strength of the output drivers does not stop the degradation at the higher frequencies depending on particular channel performances.
It would be desirable to implement an asymmetrical emphasis in a memory data bus driver.